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Discussion Starter #1
I've recently bought a 92 2.0lt 100 estate. When I first got it the brake master cylinder was leaking so I took it to a local garage to have it changed. While being changed they noticed that the head gasket was leaking and asked to change it, which they did. After 100 miles it started to overheat. They changed the thermostat, flushed the system several times but now within 5 minutes of starting the engine overheats. The coolant pressurises and blows off the weakest joint. They are at a loss to understand why. Anyone have any ideas
 

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If the cooling system is pressurising to the point of blowing off secure pipes it sounds like head gasket to me.

Did have a CX diesel years ago and that had similar overheating symptoms, (not blowing off pipes though), but was down to the expansion tank cap not venting.

basically the cooling system requires about 1 bar to work efficiently any excess due to the engine working hard or high ambient for instance with be vented via a preset pressure valve in the header tank / expansion tank cap.

Anyway yours sounds like the head gasket to me, either they didn't follow the correct procedure, they used a poor quality/ faulty gasket or there are other factors head / block not flat, (were they checked?). Is there any oil in the water water in the oil? can you smell exhaust fumes in the coolant?
 

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Did they pressure test the head for any cracks?Is your car running rough apart from the overheating?Could be a crack in the head from gasket failure which would require head off for re skimming
 

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Discussion Starter #6
I went to garage today and can report on following. No water in oil. Nothing in water. Engine runs fine from cold for 6 minutes then pressurises and blew off head to rad hose. Water at this point was boiling. Heater matrix cold (Control set to hot). Rad is not very warm. New Audi head gasket fitted. Block visually checked, head, pressure checked. I drained rad and put in a tin of Wynns coolant cleaner which lasted 6 minutes. After cooling down refilled system and tried again. Same result after 3-4 minutes. Going to try changing the pump just in case. What I did notice is there are no bleed vents in the system, are there supposed to be? If not how to you get any air out of the heater and inlet/exit pipes.
Thanks
 

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Still sounds like a head gasket to me, especially the fact it seemed ok for 100 miles after the initial repair.

The water pump is a simple item and I can't see it not working. If the front part is being driven by the belt then the impeller inside must be going round unless it's fallen off which is pretty much unheard of, I doubt the impeller has enough space to go anywhere and I think it's all that stops the belt driven end coming off. Water pump faults are mainly leaking, or not going around at all because the coolant has frozen due to lack of antifreeze in the system.

Not sure on your model, but you should find some bleed points under the tray at the back of the engine compartment where the heater hoses go into the heater, they are small thumb wheels built into the coolant hoses, (at least the UK spec TDI version with a/c has them..)

You could also try one of the headgasket repair additives you put in the cooling system. Not the best way to solve IMO, but if it works even temporally it will confirm it's headgasket or, (more unlikely but still possible), a cracked head or block.

Cylinder head bolt torque sequence and staging can be critical to some engines, I remember the Peugeot 505 / 604 TD engine, if the very complicated head bolt torque sequence with heat cycles wasn't followed rigidly to the letter the gasket would go again pretty soon. Shouldn't be such an issue with a petrol engine, but it can be compounded by other factors. Just because the headgasket has been done doesn't mean it was done correctly or with the correct gasket, I've also come across quite a few faulty new parts, for instance a JCB clutch with a rivet sticking out and an Opel manta clutch that wasn't round!!
 

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Discussion Starter #8
OK, thanks for your comments. I have an update from the garage. At some time in the past someone has used what looks like 'radweld' and a LOT of it. They have been taking some of the cooling pipes off and flushing them thru. In some of the lower parts they have discovered a lot of solid 'sludge' which comes out in lumps. I spoke to Holts who make radweld and they don't know of anything that will shift it. I have a new rad which I will fit anyway but has anyone used anything which will dissolve or dislodge the stuff. It seems to be in the block that most of it is stuck. Anyone used 'something' to good effect.
 

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Umm... sounds odd to me. If it were blocked before and if this were causing the overheating then how come it did 100 miles after the gasket repair? that's a good 2 hours driving...

Doesn't sound good, even if you get it all out... why was it there? why so much of it and is / was it hiding a cracked block / head or other problem..

Not what you may want to hear but I'd be looking for a second-hand engine by now, because you could keep throwing money at this one without knowing if it can be fixed :puzzled:
 

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Discussion Starter #10
Thanks bladerunner :liebe011: . The garage who have the car at the moment have asked me to take it away. They will NOT charge a penny for the work carried out so far. Its taking up valuable space so they want it out of the way as they seem unable to solve the problem. I spoke to the previous owner who had it for 6 months. During that time he did nothing to it even missed oil check. He got it from a 'mate' who had it for 4 years. He had lots of cars and did 'lots of things to them'. I know the rad leaked a little hence getting a new one off Ebay (yet to be fitted). The heater matrix condition is not known as it has not worked. I thought it was thermostat as engine didn't get hot. Having looked at the pipework I feel that one of the pipes into the heater is blocked and is causing an airlock somewhere. Once I get the car home I will take off each pipe and connect a garden hose and flush the hole system out. I spoke to my local Audi dealer who were very helpful. I explained my problem and they told me to try the flushing bit by bit. They also confirmed that there is NO bleed valves in the system. You need to release the header tank and lift it as high as possible. To quote 'it can be a pain to bleed'. :clap:
I keep you posted. :w00t:
 

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Obviously from my point of view it's not easy to fully diagnoses 3rd hand, but I'm still not understanding why it was ok for 100 miles after the initial head repair?

If it were all blocked with this gunge causing it to overheat before then what changed during the head gasket change to make it behave for a while?

Did the heater work before the garage attempt the head gasket repair?

If yes then maybe they added this "headgasket repair gunge" to the system in and attempt to solve it when the head gasket replacement failed, and did "solve" it temporally for 100 miles or so. (sorry to be sceptical but my experience of car repairers means I'd trust most of them as far as I could throw them, and is partly why I do everything myself). The fact they are not charging you would make me more suspicious that pleased.....

Anyway you wont loose anything, (except time and sanity), trying to clean out the gunge from the system, but I do advise you not to throw any more money at an unknown and possible unfixable engine. I guess it depends on secondhand spares availability where you are. Not sure where you are in the country but locating a cheap good 2.0 lump should be pretty easy in the UK.....

http://www.4ringspares.co.uk/

http://www.allaudi.co.uk/

On the bleed points, I'm talking later A6 version with A/C, (as I've not had a 100), so maybe it was something they added due to the bleed issues with the 100 version?

One last thing....... I'm pretty sure I have a good second-hand heater matrix in my spares. It's from an A6 version but I think they are the same. If you find yours is all blocked up I will be happy to donate it for postage costs if it'll help you out :57:
 

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Discussion Starter #12
Thanks again BladeRunner :liebe011: :liebe011: :liebe011:
I will bear your offer in mind.
I spoke with the spanner at the garage rather than the oily rag today. I may have been mislead or misunderstood the problem. Apparantly when I first took the car in for the brake master cylinder to be changed they discovered there was a fault with a rear calliper. This was changed as well. During the change air kept getting into the system and the brakes acted like 'air brakes' either on or off. During all of the road tests it clocked up about 80 miles. It was after this that they found a small leak at the back of the head gasket under the servo unit. The head was removed, cleaned, checked and replaced. It is now that the current problem started. Within minutes of starting it boils. They changed the thermostat and a pipe that had collapsed. They checked the water pump which seemed OK so was replaced. The heater matrix was full of brown stuff which they attempted to blow clear with steam. They think that a lump of this has lodged somewhere in the system. When the engine runs from cold the heater stays cold. The rad gets luke warm whilst the block gets very hot and boils.
I had the car for a few weeks before I took it into the garage. I covered 800 miles with a trailer on the back and apart from a lack of heat from the heater it drove fine.
I would also say that the garage concerned is a 'main' dealer for another manufacturer who I have used for two years without a problem.
 

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I'm still sceptical of the repairers competence from your description so far, if your car has ABS it sounds as if they let air get trapped in the ABS unit as that will give the type of symptoms you are describing, and it is a right royal pain in the @ss to bleed out without the Audi high pressure bleed system. If you've haven't got ABS then I don't know what they did???

Anyhow are you sure the blockage / brown stuff is not hardened rust / rust sludge? (maybe different to the stuff in the block?). People often top up cooling systems with plain tap water only causing serious corrosion over time accelerated by the "battery effect" of an iron block & alloy head? Mine was pretty bad in this department when I got it, and my heater not very good either, along with a pretty clogged rad. I've since flushed mine many times and it now has 50/50 Glycol based antifreeze / distilled water in it with a new rad, matrix and heater hoses. Why do people do it? antifreeze / summer coolant is so cheep, but the damage plain water can do is huge.....

Sounds like yours is all blocked up like mine but maybe worse however that doesn't explain why it was running ok before you had them "repair" it. Rust wont block it up to that degree overnight, it would slowly get worse and overheat underload or on hot days initially...

Here's another thought:-

Yours was like mine, rust in the rad block & heater from years of use in the past with no coolant protection. They "fixed" the headgasket issue? but it was pressurising the coolant or some issue after the repair, so they added one of those cracked head / block repair solutions to the cooling system. However due to the rust sludge in the system this stuff settled and hardened all the rust deposits / sludge turning in to something more akin to rock. now the cooling system that was just about coping is virtually blocked leading to the overheating issues you now have.....

Anyhow I could speculate until the cows come home I guess by whatever I'd still be less impressed that you took in a car that was running fine, (other than the possibly unrelated heater issue), and they have appeared to have caused problems with questionably unnecessary "repair" work. The fact they have a franchise from some car maker cuts no ice with me either, main dealers are just expensive average joe car repairers, with pretty, (expensive), showrooms, specialising in one make. They are often no more, but quite often less competent than the average Joe garage without an official car makers name over the door.

Do let me know what the upshot is when you find a solve?, and Btw, the spare matrix I have is a good one from another car, the old one from my car I threw away as it was too blocked up....

:thumbsup:
 

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Just like to to some good posting going on here... keep it up.. BladeRunner & flashman!

Cheers
 

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Discussion Starter #15
Car was returned home to me tonight :hyper:
The chief mechanic brought it home on a trailer and gave me the lowdown. As last post give details I won't repeat other than to add that the plastic outlet connector from the head to the rad top hose was broken. It had been cracked for a while looking at the sludge build up in it. It was letting in air and eventually blew apart under pressure, three miles out on test run :w00t: . The rad was leaking so they added a tin of radweld. after this is when the fun started and the boiling began. I'm off to the local Audi dealer to get a new connector tomorrow and then will commence the flushing procedure.
If I get it running what antifreeze do you recommend. Is the accessory shop stuff as good as Audi's own brand, I know its cheaper :grin: :grin:
I will post on the progress.

Thanks for your comments RickT :liebe011:
 

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Great, I hope it turns out ok, but if not I came across this whilst ebaying this evening:-

Type this number into the ebay search feature 4627509022

As far as antifreeze is concerned any known make will be ok, avoid the super cheep "acme" brands... think I'm using Castrol atm, just make sure it's Glycol based, and not a methanol mix, (don't think you can get them any more but old stock is probably still about). If you have pets, (esp cats), or young children and don't want any risk, then consider a "Triguard" mono propylene glycol antifreeze which is virtually harmless, compared to the sweet tasting very poisonous standard glycol based stuff...... but alas more expensive.

You can also buy many "premixed" if you prefer but again it tends to be more costly.

What I usually do is buy 5 litres of Glycol concentrate & 5 litres of de-ionised or distilled water, depending on what's available, (but you can use tap water if it's not excessively hard in your area).

I then mix them together in a bucket and re-decant to the 5 litre containers, the car should take about 5 litres give or take so use the mix from the water container first, and you should be left with most of the antifreeze container as a ready to use dilute at 50%. Mark it as such with a permanent ink and store safely. It can be used to top up if you get leaks, without diluting the antifreeze concentration, or redo at a later date..

Another tip, if you get a car new to you of unknown history and are unsure of antifreeze % or protection, you can buy a specific gravity tester, but a simple "free" test is to siphon off a small amount and seal in a small plastic container, (mark it very clearly as antifreeze sample), and place in the bottom of your deep freezer.. if it is still fully liquid after a day or so your antifreeze is good for winter, unless you plan on driving to Siberia for your winter hols :w00t:

For the time being though don't add any antifreeze to your car until you know it's ok, (unless where you are is likely to go below freezing during this period), system should also be flushed it through until all that rust etc is out of the system. A week or so with plain water wont make any appreciable corrosion difference to the system while you check / clean it all out.
 

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Discussion Starter #17
OK are you all sitting comfortably, then I shall begin.
Replaced the head to rad connector tonight. Old one had been well botched in past using what looks like window mastic. Connected all the pipes up and topped up with water. Started up and it ran for 4-5 minutes OK. At this time the bottom hose was cold, The heater hose inlet was hot, outlet was warm. Small pipe from head/rad junction was hot. Big pipe from head/rad junction to rad was hot up till a join with a small pipe which goes off down to a metal box (small pipe warm). From this join to the rad was cold. There were a few bubbles in the header tank and you could hear air??? in the small pipes around the heater area. At about 6 minutes I noticed water running from under the car. Close inspection found that on the bottom of the header tank is a protusion with two electrical wires, just behind power steering tank, this was leaking. Cannot see in the Haynes what this is, so what is it please. Is it a new tank??
Got dark and chilly so :beer: :beer: :beer:
 

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Still sounds like the system is pressurising, but it's so hard to be totally sure without being there first hand :unsure: Are the hoses hard when it's running before? & after it gets warm?. What happens if you remove the header tank cap, (before it's warmed up)?. Assuming for the moment just for arguments sake it is pressurising, it's possible whatever is pressurising the coolant only opens up when it gets to a certain temp. Often even minor pressurisation causes the engine to overheat because the pressure affects the current flow of the coolant around the system...

Anyhow I think you'll find the header tank has a low level sensor, (mine has), a warning will appear in the dash, (in the check system if yours has it), when the coolant level drops below a certain point. This is most likely the sensor you have in the header tank. Usually they are removable with an o-ring, can't remember off the top of my head how this one is done, but you can take the header tank off and have a look, the wires should be on a plug of some sort.

Also the rad should remain cold until the engine is fully up to temperature before the thermostat opens, (to hot for you to touch and leave your finger on). In the winter I have to fast idle my TDI for 30 mins or so before the Thermo stat opens although petrol's warm up much quicker.
 

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Discussion Starter #19
Tonights saga.
Checked header tank and there is a small split around the sensor. Put some mastic in for testing. Header was empty when I checked today it had leaked out of split. Took off three of the smaller pipes and pushed a garden hose through them and flushed it all out. Refilled system and started up. Pipes were soft on starting and a few air bubles in header tank. After 5 minutes top hose was hot, heater was luke warm and rad cold. No bubbles. 10 minutes top hose hot to rad, heater warm and all pipes hard. 15 minutes top hose hot, heater warm/hot, bottom hose cold and rad hot on pipe side cold on o/s. 25 minutes everything hot and hard. Heater outlet warm so I think maybe air in heater. Radiator fans cut in for 30 secs and engine cuts out. I thought it had run out of petrol. Went to garage and put 5 litres in and she started up ran for 5 minutes and fans comes on and engine cuts out.
Time to go out so new header tank tomorrow and try again. Any thoughts on why it cuts out please.
 

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Discussion Starter #20
It works :hyper: :hyper: :hyper: :hyper: :hyper:

Spent the afternoon giving it another flush through having left a tin of Wynns cleaner in for 24 hours. It spent the last 4-5 years in a very hard water area and there was a lot of chalky deposits came out. Had to put a new battery in as old one was shot and started her up. Ran for 5 mins, no problem. 10 Minutes no probs, heater is not hot but rest of system is. Ran it for 30 minutes until the fuel warning buzzer started. I thought that maybe it was time to try giving it a run. So off down to the petrol station and a few trips around the block and back home. Checked everything and all OK so took it out for a longer run. 20 miles at 60mph on a motorway with a few more miles on normal roads and it ran like a dream.
All I need to do now is sort out the ABS/air problem and I am sorted. Sunday is new radio fitting day.
Thanks to all those who responded to my plea for help. :liebe011: :liebe011:
 
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